Excitation wavelength dependence of the charge separation pathways in tetraporphyrin-naphthalene diimide pentads.

The excited-state dynamics of two multichromophoric arrays composed of a naphthalene diimide centre and four zinc or free-base porphyrins substituted on the naphthalene core via aniline bridges has been investigated using a combination of stationary and ultrafast spectroscopy. These pentads act as efficient antennae as they absorb over the whole visible region, with a band around 700 nm, associated with a transition to the S1 state delocalised over the whole arrays, and bands at higher energy due to transitions centred on the porphyrins. In non-polar solvents, population of these porphyrin states is followed by sub-picosecond internal conversion to the S1 state.

Excited-state dynamics of porphyrin-naphthalenediimide-porphyrin triads.

The excited-state dynamics of two triads consisting of a naphthalenediimide (cNDI) substituted at the core by two zinc (ZnP) or free-base tetraphenylporphyrins (FbP) was investigated by ultrafast fluorescence and transient absorption spectroscopy. The electronic absorption spectra of the triads are almost the composites of those of the constituents, pointing to a weak electronic coupling and to a localization of the excitation energy on one of the porphyrins. In cyclohexane, the excited-state dynamics of the triads are essentially the same as those of the individual porphyrins, with the exception of the Soret emission of the ZnP triad, whose lifetime exhibits a more than 10 fold shortening compared to ZnP.

Supramolecular construction of vesicles based on core-substituted naphthalene diimide appended with triethyleneglycol motifs.

The self-assembly of core-substituted naphthalene diimides bearing triethylene glycol motifs leads to the formation of stable vesicles in DMSO and CHCl(3)/MeOH (6 : 4, v/v) solvents. The vesicles were evaluated by means of UV/vis and fluorescence spectroscopy, transmission electron microscopy, atomic force microscopy and dynamic light scattering.

Nonradiative deactivation of excited hemicyanines studied with submolecular spatial resolution by time-resolved surface second harmonic generation at liquid-liquid interfaces.

The excited-state dynamics of aminostilbazolium dyes is known to be dominated by nonradiative deactivation through large-amplitude motion. In order to identify the coordinate(s) responsible for this process, the excited-state lifetimes of two dialkylaminostyryl-methylpyridinium iodides have been measured at liquid-liquid interfaces using time-resolved surface second harmonic generation. We found that the decay time of the excited-states of both compounds was increasing with the viscosity of the apolar phase, consisting of n-alkanes of varying length, but was unaffected by that of the polar phase, made of water/glycerol mixtures.